organic compounds
2-Isopropyl-5-methylcyclohexyl 5-acetoxy-1,3-oxathiolane-2-carboxylate
aDepartment of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland, bDepartment of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India, and cSequent Scientific Limited, New Mangalore 575 011, India
*Correspondence e-mail: mkubicki@amu.edu.pl
In the title compound, C16H26O5S, the oxathiolane ring adopts an with the S atom 0.793 (3) Å out of the mean plane of the remaining four atoms. The cyclohexane ring of the menthol fragment adopts an almost ideal chair conformation, with all substituents in the equatorial positions. In the crystal, relatively strong, short and linear C—H⋯O hydrogen bonds link the molecules into the chains along [100] direction. The chains are packed into the by means of weak dispersive interactions. Intermolecular C—H⋯S interactions are also observed.
Related literature
The title compound is a drug intermediate of lamivudine, a reverse transcriptase inhibitor used in the treatment of HIV infections. For the structures of lamivudine and its hydrate have been studied, see: Harris et al. (1997). For the identification of lamivudine conformers by Raman scattering measurements and quantum chemical calculations, see: Pereira et al. (2007). For asymmetry parameters, see: Duax & Norton (1975). For a description of the Cambridge Structural Database, see: Allen (2002).
Experimental
Crystal data
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Data collection: CrysAlis Pro (Oxford Diffraction, 2009); cell CrysAlis Pro; data reduction: CrysAlis Pro; program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Stereochemical Workstation Operation Manual (Siemens, 1989); software used to prepare material for publication: SHELXL97.
Supporting information
10.1107/S1600536809046492/jh2112sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536809046492/jh2112Isup2.hkl
To a mixture of L-menthyl-5-hydroxy-1,3-oxathiolane-2-carboxylate (1.5 g, 5.2 m mol) in pyridine (30 ml), acetic anhydride (6.4 ml) was added slowly at 273 K (Fig. 4). The mixture was allowed to attain room temperature and stirred over night, then quenched to ice cold water and extracted with ethyl acetate. The organic layer was concentrated under vacuum to obtain the product. X-ray quality crystals were grown from slow evaporation of methanol solution (m.p.: 333–335 K).
Positional parameters of the hydrogen atoms were freely refined, the Uiso values of these atoms were set at 1.2 (1.5 for methyl groups) times Ueq of their carrier carbon atom.
Data collection: CrysAlis PRO (Oxford Diffraction, 2009)); cell
CrysAlis PRO (Oxford Diffraction, 2009)); data reduction: CrysAlis PRO (Oxford Diffraction, 2009)); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Stereochemical Workstation Operation Manual (Siemens, 1989); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).C16H26O5S | F(000) = 712 |
Mr = 330.43 | Dx = 1.264 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 3953 reflections |
a = 5.329 (1) Å | θ = 3.0–75.3° |
b = 13.867 (1) Å | µ = 0.21 mm−1 |
c = 23.490 (2) Å | T = 100 K |
V = 1735.8 (4) Å3 | Prism, colourless |
Z = 4 | 0.3 × 0.3 × 0.15 mm |
Oxford Diffraction Xcalibur Sapphire2 large Be window diffractometer | 3632 independent reflections |
Radiation source: Nova (Mo) X-ray Source | 3175 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.025 |
Detector resolution: 5.2679 pixels mm-1 | θmax = 27.8°, θmin = 2.9° |
ω scans | h = −6→6 |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | k = −17→19 |
Tmin = 0.719, Tmax = 1.000 | l = −18→28 |
11503 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.028 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.053 | w = 1/[σ2(Fo2) + (0.026P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max = 0.001 |
3632 reflections | Δρmax = 0.28 e Å−3 |
277 parameters | Δρmin = −0.18 e Å−3 |
0 restraints | Absolute structure: Flack (1983), 1435 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.04 (5) |
C16H26O5S | V = 1735.8 (4) Å3 |
Mr = 330.43 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 5.329 (1) Å | µ = 0.21 mm−1 |
b = 13.867 (1) Å | T = 100 K |
c = 23.490 (2) Å | 0.3 × 0.3 × 0.15 mm |
Oxford Diffraction Xcalibur Sapphire2 large Be window diffractometer | 3632 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | 3175 reflections with I > 2σ(I) |
Tmin = 0.719, Tmax = 1.000 | Rint = 0.025 |
11503 measured reflections |
R[F2 > 2σ(F2)] = 0.028 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.053 | Δρmax = 0.28 e Å−3 |
S = 1.03 | Δρmin = −0.18 e Å−3 |
3632 reflections | Absolute structure: Flack (1983), 1435 Friedel pairs |
277 parameters | Absolute structure parameter: −0.04 (5) |
0 restraints |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.2221 (3) | 0.81153 (11) | 0.22603 (6) | 0.0144 (3) | |
H1 | 0.055 (3) | 0.7890 (12) | 0.2363 (5) | 0.017* | |
C2 | 0.2271 (3) | 0.92125 (11) | 0.22689 (6) | 0.0133 (3) | |
H2 | 0.402 (3) | 0.9383 (11) | 0.2176 (6) | 0.016* | |
C21 | 0.1670 (3) | 0.96521 (11) | 0.28540 (6) | 0.0163 (3) | |
H21 | 0.277 (3) | 0.9324 (11) | 0.3133 (7) | 0.020* | |
C22 | −0.1041 (3) | 0.95024 (13) | 0.30376 (8) | 0.0248 (4) | |
H22A | −0.139 (3) | 0.9755 (13) | 0.3442 (8) | 0.037* | |
H22B | −0.154 (3) | 0.8837 (14) | 0.3016 (7) | 0.037* | |
H22C | −0.216 (3) | 0.9878 (14) | 0.2804 (8) | 0.037* | |
C23 | 0.2308 (3) | 1.07241 (12) | 0.28675 (7) | 0.0207 (4) | |
H23A | 0.126 (3) | 1.1091 (13) | 0.2621 (7) | 0.031* | |
H23B | 0.396 (3) | 1.0834 (12) | 0.2739 (7) | 0.031* | |
H23C | 0.207 (3) | 1.0990 (12) | 0.3264 (7) | 0.031* | |
C3 | 0.0559 (3) | 0.95554 (11) | 0.17848 (6) | 0.0193 (3) | |
H3A | −0.122 (3) | 0.9338 (12) | 0.1888 (7) | 0.023* | |
H3B | 0.049 (3) | 1.0270 (12) | 0.1771 (6) | 0.023* | |
C4 | 0.1377 (3) | 0.91614 (12) | 0.12123 (7) | 0.0222 (4) | |
H4A | 0.300 (3) | 0.9392 (12) | 0.1134 (7) | 0.027* | |
H4B | 0.025 (3) | 0.9406 (12) | 0.0913 (7) | 0.027* | |
C5 | 0.1436 (3) | 0.80595 (12) | 0.12053 (6) | 0.0199 (4) | |
H5 | −0.025 (3) | 0.7843 (12) | 0.1282 (6) | 0.024* | |
C51 | 0.2389 (4) | 0.76739 (13) | 0.06413 (8) | 0.0305 (4) | |
H51A | 0.398 (4) | 0.7932 (14) | 0.0557 (7) | 0.046* | |
H51B | 0.137 (3) | 0.7914 (15) | 0.0335 (8) | 0.046* | |
H51C | 0.245 (3) | 0.6975 (14) | 0.0650 (8) | 0.046* | |
C6 | 0.3052 (3) | 0.76948 (11) | 0.16982 (6) | 0.0172 (3) | |
H6A | 0.478 (3) | 0.7877 (12) | 0.1612 (6) | 0.021* | |
H6B | 0.305 (3) | 0.6970 (12) | 0.1714 (6) | 0.021* | |
O11 | 0.39944 (16) | 0.77425 (7) | 0.26904 (4) | 0.0146 (2) | |
C12 | 0.3058 (3) | 0.72616 (10) | 0.31299 (6) | 0.0134 (3) | |
O12 | 0.08816 (18) | 0.70999 (9) | 0.32180 (4) | 0.0214 (2) | |
C13 | 0.5134 (3) | 0.69492 (11) | 0.35302 (6) | 0.0146 (3) | |
H13 | 0.672 (3) | 0.6830 (11) | 0.3325 (6) | 0.018* | |
S14 | 0.56357 (7) | 0.79072 (3) | 0.404699 (15) | 0.01686 (9) | |
C15 | 0.3109 (3) | 0.73820 (11) | 0.44548 (6) | 0.0176 (3) | |
H15A | 0.327 (3) | 0.7581 (11) | 0.4845 (7) | 0.021* | |
H15B | 0.150 (3) | 0.7576 (11) | 0.4298 (7) | 0.021* | |
C16 | 0.3439 (3) | 0.63111 (12) | 0.43767 (6) | 0.0189 (3) | |
H16 | 0.175 (3) | 0.5948 (11) | 0.4441 (6) | 0.023* | |
O17 | 0.4379 (2) | 0.61176 (7) | 0.38320 (4) | 0.0205 (2) | |
O18 | 0.52454 (18) | 0.59729 (7) | 0.47832 (4) | 0.0206 (2) | |
C19 | 0.4838 (3) | 0.50989 (11) | 0.50215 (6) | 0.0193 (3) | |
O19 | 0.3034 (2) | 0.46223 (9) | 0.49229 (6) | 0.0418 (4) | |
C20 | 0.6923 (3) | 0.48274 (13) | 0.54115 (7) | 0.0252 (4) | |
H20A | 0.709 (3) | 0.5287 (14) | 0.5686 (8) | 0.038* | |
H20B | 0.850 (3) | 0.4807 (13) | 0.5212 (8) | 0.038* | |
H20C | 0.659 (3) | 0.4227 (13) | 0.5576 (7) | 0.038* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0124 (7) | 0.0178 (9) | 0.0129 (8) | −0.0003 (7) | −0.0033 (6) | 0.0033 (6) |
C2 | 0.0115 (7) | 0.0157 (8) | 0.0127 (8) | −0.0026 (6) | −0.0008 (6) | 0.0021 (6) |
C21 | 0.0179 (8) | 0.0171 (8) | 0.0137 (8) | 0.0017 (7) | −0.0020 (6) | 0.0002 (6) |
C22 | 0.0232 (9) | 0.0248 (10) | 0.0265 (10) | −0.0013 (8) | 0.0080 (8) | −0.0066 (7) |
C23 | 0.0247 (9) | 0.0181 (9) | 0.0192 (10) | 0.0005 (7) | −0.0012 (7) | −0.0027 (7) |
C3 | 0.0246 (9) | 0.0149 (8) | 0.0184 (8) | 0.0007 (8) | −0.0050 (7) | 0.0025 (6) |
C4 | 0.0310 (10) | 0.0200 (9) | 0.0157 (8) | −0.0019 (7) | −0.0068 (7) | 0.0038 (7) |
C5 | 0.0255 (8) | 0.0188 (9) | 0.0155 (8) | −0.0053 (7) | −0.0037 (6) | −0.0011 (7) |
C51 | 0.0474 (12) | 0.0260 (11) | 0.0180 (9) | −0.0037 (10) | −0.0045 (8) | −0.0035 (8) |
C6 | 0.0198 (8) | 0.0142 (9) | 0.0175 (8) | 0.0005 (7) | 0.0004 (6) | −0.0005 (6) |
O11 | 0.0124 (5) | 0.0178 (6) | 0.0137 (5) | 0.0008 (5) | −0.0006 (4) | 0.0037 (4) |
C12 | 0.0159 (8) | 0.0115 (8) | 0.0126 (8) | −0.0005 (6) | 0.0010 (6) | −0.0021 (6) |
O12 | 0.0138 (5) | 0.0287 (6) | 0.0218 (6) | −0.0059 (5) | −0.0009 (4) | 0.0072 (5) |
C13 | 0.0158 (8) | 0.0156 (8) | 0.0124 (7) | 0.0031 (6) | 0.0013 (5) | −0.0005 (6) |
S14 | 0.01923 (18) | 0.01732 (18) | 0.01403 (18) | −0.00361 (17) | −0.00206 (15) | 0.00048 (16) |
C15 | 0.0176 (8) | 0.0250 (9) | 0.0101 (8) | 0.0018 (7) | 0.0015 (6) | 0.0009 (6) |
C16 | 0.0186 (8) | 0.0236 (9) | 0.0145 (8) | −0.0040 (8) | −0.0029 (6) | 0.0058 (7) |
O17 | 0.0326 (6) | 0.0136 (5) | 0.0153 (5) | 0.0006 (5) | −0.0039 (5) | 0.0012 (4) |
O18 | 0.0229 (6) | 0.0205 (6) | 0.0183 (5) | −0.0065 (5) | −0.0073 (4) | 0.0079 (4) |
C19 | 0.0224 (8) | 0.0180 (8) | 0.0174 (8) | −0.0002 (7) | 0.0028 (6) | 0.0046 (6) |
O19 | 0.0291 (6) | 0.0330 (8) | 0.0632 (9) | −0.0137 (6) | −0.0157 (6) | 0.0248 (7) |
C20 | 0.0335 (10) | 0.0230 (10) | 0.0193 (9) | −0.0006 (8) | −0.0049 (8) | 0.0050 (8) |
C1—O11 | 1.4768 (16) | C51—H51A | 0.94 (2) |
C1—C6 | 1.510 (2) | C51—H51B | 0.961 (18) |
C1—C2 | 1.522 (2) | C51—H51C | 0.970 (19) |
C1—H1 | 0.975 (15) | C6—H6A | 0.975 (15) |
C2—C3 | 1.533 (2) | C6—H6B | 1.006 (16) |
C2—C21 | 1.537 (2) | O11—C12 | 1.3264 (16) |
C2—H2 | 0.986 (15) | C12—O12 | 1.1991 (16) |
C21—C22 | 1.522 (2) | C12—C13 | 1.5155 (19) |
C21—C23 | 1.525 (2) | C13—O17 | 1.4122 (17) |
C21—H21 | 0.990 (16) | C13—S14 | 1.8193 (15) |
C22—H22A | 1.029 (19) | C13—H13 | 0.989 (15) |
C22—H22B | 0.961 (19) | S14—C15 | 1.8059 (16) |
C22—H22C | 0.965 (18) | C15—C16 | 1.507 (2) |
C23—H23A | 0.951 (17) | C15—H15A | 0.961 (16) |
C23—H23B | 0.945 (18) | C15—H15B | 0.973 (15) |
C23—H23C | 1.009 (17) | C16—O17 | 1.4000 (18) |
C3—C4 | 1.515 (2) | C16—O18 | 1.4345 (17) |
C3—H3A | 1.024 (16) | C16—H16 | 1.042 (16) |
C3—H3B | 0.992 (16) | O18—C19 | 1.3526 (17) |
C4—C5 | 1.528 (2) | C19—O19 | 1.1891 (17) |
C4—H4A | 0.941 (18) | C19—C20 | 1.489 (2) |
C4—H4B | 0.983 (16) | C20—H20A | 0.911 (19) |
C5—C51 | 1.516 (2) | C20—H20B | 0.961 (18) |
C5—C6 | 1.529 (2) | C20—H20C | 0.936 (18) |
C5—H5 | 0.965 (15) | ||
O11—C1—C6 | 106.00 (11) | C6—C5—H5 | 106.3 (9) |
O11—C1—C2 | 109.26 (12) | C5—C51—H51A | 110.6 (11) |
C6—C1—C2 | 113.12 (13) | C5—C51—H51B | 109.9 (11) |
O11—C1—H1 | 107.7 (8) | H51A—C51—H51B | 102.8 (15) |
C6—C1—H1 | 111.1 (8) | C5—C51—H51C | 110.2 (11) |
C2—C1—H1 | 109.5 (10) | H51A—C51—H51C | 110.8 (17) |
C1—C2—C3 | 106.85 (12) | H51B—C51—H51C | 112.3 (17) |
C1—C2—C21 | 113.86 (13) | C1—C6—C5 | 111.69 (12) |
C3—C2—C21 | 114.59 (13) | C1—C6—H6A | 111.0 (9) |
C1—C2—H2 | 104.7 (9) | C5—C6—H6A | 106.8 (9) |
C3—C2—H2 | 108.9 (8) | C1—C6—H6B | 110.7 (9) |
C21—C2—H2 | 107.4 (8) | C5—C6—H6B | 111.0 (9) |
C22—C21—C23 | 109.79 (14) | H6A—C6—H6B | 105.5 (13) |
C22—C21—C2 | 113.39 (13) | C12—O11—C1 | 117.88 (11) |
C23—C21—C2 | 111.01 (13) | O12—C12—O11 | 126.32 (13) |
C22—C21—H21 | 108.3 (9) | O12—C12—C13 | 123.07 (13) |
C23—C21—H21 | 107.6 (9) | O11—C12—C13 | 110.60 (11) |
C2—C21—H21 | 106.5 (9) | O17—C13—C12 | 109.67 (12) |
C21—C22—H22A | 112.7 (9) | O17—C13—S14 | 107.65 (9) |
C21—C22—H22B | 112.2 (10) | C12—C13—S14 | 108.21 (10) |
H22A—C22—H22B | 109.0 (15) | O17—C13—H13 | 110.7 (9) |
C21—C22—H22C | 110.8 (11) | C12—C13—H13 | 111.7 (9) |
H22A—C22—H22C | 103.2 (14) | S14—C13—H13 | 108.8 (9) |
H22B—C22—H22C | 108.5 (15) | C15—S14—C13 | 87.13 (7) |
C21—C23—H23A | 112.2 (10) | C16—C15—S14 | 104.23 (11) |
C21—C23—H23B | 111.0 (11) | C16—C15—H15A | 112.8 (9) |
H23A—C23—H23B | 105.6 (14) | S14—C15—H15A | 108.9 (9) |
C21—C23—H23C | 110.4 (10) | C16—C15—H15B | 109.2 (9) |
H23A—C23—H23C | 107.0 (14) | S14—C15—H15B | 110.3 (9) |
H23B—C23—H23C | 110.5 (14) | H15A—C15—H15B | 111.1 (13) |
C4—C3—C2 | 112.04 (14) | O17—C16—O18 | 107.80 (12) |
C4—C3—H3A | 111.7 (9) | O17—C16—C15 | 109.99 (12) |
C2—C3—H3A | 106.5 (9) | O18—C16—C15 | 108.64 (12) |
C4—C3—H3B | 110.0 (8) | O17—C16—H16 | 110.4 (8) |
C2—C3—H3B | 110.9 (9) | O18—C16—H16 | 109.0 (8) |
H3A—C3—H3B | 105.5 (13) | C15—C16—H16 | 111.0 (8) |
C3—C4—C5 | 112.08 (13) | C16—O17—C13 | 113.85 (11) |
C3—C4—H4A | 108.4 (10) | C19—O18—C16 | 117.42 (11) |
C5—C4—H4A | 108.6 (10) | O19—C19—O18 | 123.18 (13) |
C3—C4—H4B | 109.6 (9) | O19—C19—C20 | 125.64 (15) |
C5—C4—H4B | 110.5 (9) | O18—C19—C20 | 111.18 (13) |
H4A—C4—H4B | 107.6 (13) | C19—C20—H20A | 109.4 (11) |
C51—C5—C4 | 111.65 (14) | C19—C20—H20B | 111.1 (10) |
C51—C5—C6 | 110.89 (13) | H20A—C20—H20B | 106.0 (16) |
C4—C5—C6 | 109.53 (13) | C19—C20—H20C | 109.6 (11) |
C51—C5—H5 | 111.4 (9) | H20A—C20—H20C | 110.5 (16) |
C4—C5—H5 | 106.9 (10) | H20B—C20—H20C | 110.1 (15) |
O11—C1—C2—C3 | 175.68 (11) | C1—O11—C12—O12 | −0.5 (2) |
C6—C1—C2—C3 | 57.86 (16) | C1—O11—C12—C13 | −179.08 (11) |
O11—C1—C2—C21 | −56.78 (16) | O12—C12—C13—O17 | 27.68 (19) |
C6—C1—C2—C21 | −174.59 (12) | O11—C12—C13—O17 | −153.67 (11) |
C1—C2—C21—C22 | −68.34 (17) | O12—C12—C13—S14 | −89.49 (16) |
C3—C2—C21—C22 | 55.10 (18) | O11—C12—C13—S14 | 89.16 (12) |
C1—C2—C21—C23 | 167.51 (14) | O17—C13—S14—C15 | −33.57 (10) |
C3—C2—C21—C23 | −69.05 (17) | C12—C13—S14—C15 | 84.90 (11) |
C1—C2—C3—C4 | −57.56 (17) | C13—S14—C15—C16 | 37.16 (10) |
C21—C2—C3—C4 | 175.32 (13) | S14—C15—C16—O17 | −33.65 (15) |
C2—C3—C4—C5 | 57.98 (18) | S14—C15—C16—O18 | 84.12 (12) |
C3—C4—C5—C51 | −176.96 (15) | O18—C16—O17—C13 | −109.17 (13) |
C3—C4—C5—C6 | −53.74 (19) | C15—C16—O17—C13 | 9.12 (17) |
O11—C1—C6—C5 | −177.46 (12) | C12—C13—O17—C16 | −97.69 (14) |
C2—C1—C6—C5 | −57.75 (17) | S14—C13—O17—C16 | 19.84 (14) |
C51—C5—C6—C1 | 176.82 (14) | O17—C16—O18—C19 | −98.38 (14) |
C4—C5—C6—C1 | 53.16 (17) | C15—C16—O18—C19 | 142.46 (13) |
C6—C1—O11—C12 | −123.41 (13) | C16—O18—C19—O19 | −2.4 (2) |
C2—C1—O11—C12 | 114.39 (14) | C16—O18—C19—C20 | 177.29 (13) |
D—H···A | D—H | H···A | D···A | D—H···A |
C13—H13···O12i | 0.989 (15) | 2.261 (15) | 3.1563 (18) | 150.0 (12) |
C15—H15A···S14ii | 0.961 (16) | 3.033 (15) | 3.7794 (15) | 135.6 (11) |
C20—H20B···O19i | 0.961 (18) | 2.524 (18) | 3.464 (2) | 166.0 (14) |
Symmetry codes: (i) x+1, y, z; (ii) x−1/2, −y+3/2, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C16H26O5S |
Mr | 330.43 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 100 |
a, b, c (Å) | 5.329 (1), 13.867 (1), 23.490 (2) |
V (Å3) | 1735.8 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.21 |
Crystal size (mm) | 0.3 × 0.3 × 0.15 |
Data collection | |
Diffractometer | Oxford Diffraction Xcalibur Sapphire2 large Be window diffractometer |
Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) |
Tmin, Tmax | 0.719, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 11503, 3632, 3175 |
Rint | 0.025 |
(sin θ/λ)max (Å−1) | 0.657 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.028, 0.053, 1.03 |
No. of reflections | 3632 |
No. of parameters | 277 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.28, −0.18 |
Absolute structure | Flack (1983), 1435 Friedel pairs |
Absolute structure parameter | −0.04 (5) |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2009)), SIR92 (Altomare et al., 1993), SHELXL97 (Sheldrick, 2008), Stereochemical Workstation Operation Manual (Siemens, 1989).
D—H···A | D—H | H···A | D···A | D—H···A |
C13—H13···O12i | 0.989 (15) | 2.261 (15) | 3.1563 (18) | 150.0 (12) |
C15—H15A···S14ii | 0.961 (16) | 3.033 (15) | 3.7794 (15) | 135.6 (11) |
C20—H20B···O19i | 0.961 (18) | 2.524 (18) | 3.464 (2) | 166.0 (14) |
Symmetry codes: (i) x+1, y, z; (ii) x−1/2, −y+3/2, −z+1. |
Acknowledgements
CSC thanks the University of Mysore for research facilities.
References
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5-Methyl-2-(propan-2-yl)cyclohexyl 5-(acetyloxy)-1,3-oxathiolane-2-carboxylate (I, Scheme 1) is a drug intermediate of lamivudine which is a reverse transcriptase inhibitor used in the treatment of HIV infection alone or in combination with other class of Anti HIV drugs. The crystal stractures of Lamivudine and its hydrate have been studied (Harris et al., 1997). The identification of lamivudine conformers by Raman scattering measurements and quantum chemical calculations is reported (Pereira et al., 2007).
The conformation of the oxathiolane ring is close to an envelope (Fig. 1), with four atoms C13, C15, C16 and O17 almost coplanar (maximum deviation from the least-squares plane of 0.0469 (11) Å) while the fifth atom (S14) is significantly, by 0.793 (3) Å out of this plane. Also the asymmetry parameter (Duax & Norton, 1975), which describes the deviation from the ideal symmetry (in this case Cs), has relatively low value of 6.0°. Similar conformation was observed in the majority of the structures with not fused oxathiolane rings found in the Cambridge Structural Database (Allen, 2002), however different atoms occupy the out-of-plane position. The acetyloxy substituent occupies the quasi-axial position with respect to the oxathiolane ring (C13—O17—C16—O18 torsion angle is -109.18 (13) °, S14—C15—C16—O18 84.13 (12) °), the position of carboxylate group is also close to the axial one (C16—O17—C13—C12 - 97.66 (14) °, C15—S14—C13—C12 84.89 (10) °). The cyclohexyl ring is close to the typical chair conformation (maximum and minimum values of the asymmetry parameters are 0.74° for ΔCs5, and 3.96° ΔC21–6), all substituents: methyl, isopropyl and carboxylate are in equatorial positions.
In the crystal structure relatively strong (short and directional) C13—H13···O12i hydrogen bonds join the molecules into the infinite chains along [100]. These chain in turn are organized into the crystal structure by weak van der Waals - type interactions (Table 1, Fig. 2).